I have a user running Word 2007 SP3/Windows 7 Pro x64 who gets the following error whenever attempting to open a file that another user has open:

"documentname.docx is locked for editing by" and says it is her who has it open. Also gives options to open a Read Only copy, create a local copy, or receive notification when the original copy is available.

Why is Word advising that she has the file open instead of naming the actual person who has it open?

Close the problem document and exit Word. See if you find a left-over file whose name starts with ~$; delete that file and restart Word. Try opening the document again.